After tracking down and infiltrating the Shadow Broker's ship, Shepard and Liara break into the Broker's intel center and confront him in person. The Shadow Broker is revealed to be a member of a pre-spaceflight race called the yahg. The yahg's brute strength knocks out one of Shepard's squad members, forcing the Commander and Liara to fight him on their own.

During the second and third stages, use the same attack method. However, techs and biotics now need to be aimed carefully, since they will have to bypass the shield he is carrying. When you aim at him, aim at his left side leg or arm. If you shoot him enough, he will stagger, which is a good time to unleash powers on him. You could also try to run behind him using the Infiltrator's cloak or the Soldier's Adrenaline Rush ability. This, combined with a charged shot from a Geth Plasma Shotgun will take him down quickly.

Once his shields and armor are taken down, run up to him quickly, and melee him. Repeat the stripping/melee process three times to finish him off.

It is useful to note that using either Liara's Singularity or Stasis will stun the Shadow Broker for a brief time, giving you the chance to inflict more damage. The effectiveness is increased if you trained Liara's mastery to "Asari Controller" since it reduces power recharge time.

The Arc Projector is very effective against the Shadow Broker. It penetrates his shield, deals damage and causes him to temporarily lower his defenses. This allows for better positioning and follow up shots with other weapons. Repeating this pattern can make short work of him even on Insanity difficulty.

You can continuously climb the two staircases in the back of the room, climbing up one, moving towards the other, climbing down then moving back to the first to keep cover between you and him, allowing you to use powers to wither his defense. The upside of doing this is as you both circle the obstacle, he will more or less ignore Liara. Any attempt to charge at her will generally result in him charging into obstacles and getting caught there, making this battle ridiculously easy.

The M-98 Widow sniper rifle is also a good choice, provided you are accurate enough to hit him behind his shield. Adrenaline Rush can help with this if you are not that accurate. If done correctly, using this tactic means you won't have to move at all throughout the fight except for the melee sequences.

Flashbang Grenades will make the Broker stagger and allow you to pepper him with gunfire for a few seconds.

If you really want any easy playthrough, then you need only confuse him so that he just stands there doing nothing. To accomplish this, head right until you're behind the pillar. If you stand close enough to the pillar to go into cover, the Broker will charge, and eventually destroy the pillar. If, on the other hand, you stand back from the pillar, enough so that the pillar is directly between you and him, the Broker will instead, just stand there. At this point, move slightly to the right, enough so that you can see him and even shoot at him, but he will not shoot back. At this point, you can just wear him down.